1. Field of the Invention
The present invention generally relates to the art of packaging and, more particularly to a bagging and packaging machine for successively forming bags from a strip of bag material and subsequently packaging an article into each of the bags.
2. Description of the Prior Art
In general, the bagging and packaging machine for successively producing bagged products by forming bags from a strip of bag material and subsequently packaging an article into each of the bag undergoes a process of forming the strip of bag material, supplied to a bag former, into a tubular form by means of the bag former by overlapping opposite longitudinal side edges with each other; fusion bonding, by means of a longitudinal sealing unit, the overlapped longitudinal side edges of the tubular strip of bag material in a direction longitudinally thereof at an outer surface of a front wall of an article introducing tube member forming a part of the bag former and, then, fusion bonding the tubular strip of bag material in a direction perpendicular to the longitudinal sense of the tubular strip of bag material to form a bottom seal by means of a transverse sealing unit; after an article has been introduced into the tubular strip of bag material through the article introducing tube member, fusion bonding an upper portion of the tubular strip of bag material by means of the transverse sealing unit to form an upper seal to seal the article within the tubular strip of bag material; and finally cutting the tubular strip of bag material along the upper seal to thereby to produce a bagged product containing the article sealed within the bag.
In the practice of this process, where the article filled in each of the successively formed bags is food material, it is a general practice to form the upper seal in the bag after an inert gas such as, for example, nitrogen gas or argon gas has been substituted for air contained in the bag containing the article therein.
The gas replacement method used in conjunction with this type of bagging and packaging machine for substituting the inert gas for the air within each of the bags includes, where a high speed handling is desired to be enhanced, supplying either continuously or intermittently of the inert gas at a predetermined flow rate into each of the bags simultaneously with filling of the article into the respective bag, to thereby purge the air within such bag.
However, in the practice of the above discussed gas replacement method, although a relatively high rate of replacement with the inert gas can be secured as a large flow of the inert gas is supplied into each of the bags, it has been found that since the amount of the inert gas supplied from the gas supply unit is relatively large, the cost of making the bagged products tends to increase correspondingly.
In addition to the foregoing problem, another problem has been found in that with the above discussed gas replacement method, to maintain the rate of gas replacement at a relatively high level, the flow velocity of the inert gas has to be increased so that the amount of the inert gas supplied per unitary time can be increased. However, increase of the gas flow velocity tends to result in that the inert gas is vigorously introduced into the bag and, consequently, some of items of the article to be bagged are blown upwardly within the bag and/or an introduction of the article towards the bottom of the bag is hampered. In such case, when the upper seal is to be formed in the filled bag by means of the transverse sealing unit, some of items of the article which have been blown upwards within the bag or which have been retarded to reach the bottom of the bag are often xe2x80x9cbittenxe2x80x9d by the transverse sealing unit, resulting in an unacceptably defective bagged product.
In an attempt to substantially eliminate the above discussed problems, the Japanese Laid-open Patent Publication No. 10-53217, for example, discloses a bagging and packaging machine in which the flow of the inert gas is varied at each of a plurality of processing stages of one cycle of forming the tubular form from the strip of the bag material, filling the article into the resultant tubular strip of the bag material and sealing the filled tubular strip with the article therein.
In the machine disclosed in the above described Japanese publication, during a period in which the article is supplied from above through the tube member into the tubular strip of the bag material then formed into an open-topped bag, the inert gas is supplied into the tubular form at a first flow rate of a value not so high to avoid upward blow-up of some of the items of the articles within the tubular form and also to avoid disturbance to a smooth introduction of the items of the article down to the bottom of the tubular form; and a period subsequent to completion of the filling of the article into the tubular form, the inert gas is supplied into the filled tubular form at a second flow rate higher than the first flow rate. The second flow rate is so chosen as to accomplish an immediate substitution of the inert gas for the air stagnating in an upper region of the interior of the tubular form while avoiding the blow-up of some of the items of the article within the tubular form.
Accordingly, the possibility can be minimized in which when the upper portion of the tubular form having the articles filled therein is to be sealed, some of the items of the article which have been blown up within the tubular form and have been retarded from reaching the bottom of the tubular form may be bitten by the sealing unit. Also, any possible undesirable increase of the amount of the inert gas supplied from the gas supply unit into the tubular form can be suppressed.
It is, however, to be noted that the bagging and packaging machine disclosed in the above discussed Japanese publication employs the inert gas supply system in which the different flow rates of the inert gas are employed for each of the processing stages of one packaging cycle to thereby substantially eliminate the above discussed problems. Hence, so long as the bagging and packaging machine is continuously run without being halted, the gas replacement rate at a relatively high level can be secured and the amount of the inert gas supplied from the gas supply unit can be minimized.
However, other than the occasion that the prior art bagging and packaging machine is halted manually by the attendant worker when the bagging and packaging operation is desired to be interrupted, it often occurs that the bagging and packaging machine is halted or temporarily interrupted by some reason. In such case, the gas supply unit incorporated in the bagging and packaging machine will continue supplying the inert gas regardless of the operating state (i.e., halted or interrupted) of the bagging and packaging machine, and therefore, the amount of the inert gas supplied, that is, the usage of the inert gas tends to be unnecessarily increased.
Also, with the prior art bagging and packaging machine of the type discussed above, the attendant worker has to bring the inert gas supply unit into inoperative position in the event of the machine being halted or interrupted temporarily, and to reopen the supply of the inert gas in the event of the machine resuming a normal operating condition. It has, however, been found that when and after the machine is resumed to the normal operating condition, a relatively long time is required for the flow rate of the inert gas being supplied to be stabilized at a predetermined value and, as a result, enhancement of the bagging and packaging operation at a high speed tends to be hampered and/or the gas replacement rate tends to be lowered.
The present invention pertains to the bagging and packaging machine of a type wherein the gas replacement takes place and aims at solving incompatible problems of attaining a relatively high gas replacement rate by sufficiently supplying the inert gas with no possibility of some of the items of the article being bitten at the time of sealing the bag and also with no possibility of the handling speed of the machine being lowered, and of minimizing the amount of the inert gas supplied from the gas supply unit.
In order to accomplish the foregoing objective of the present invention, the bagging and packaging machine in accordance with the present invention is so designed and so structured as follows.
In order to accomplish the foregoing object of the present invention, there is provided in accordance with a first aspect of the present invention, a bagging and packaging machine for forming a bag from a strip of bag material and introducing an article into the bag, which includes a gas supply means for supplying an inert gas into the bag to substitute for air contained in the bag, and a first gas supply control means for controlling supply of the inert gas by the gas supply means into the bag. The first gas supply control means is operable to effect supply of the inert gas into the bag at a first flow rate for a predetermined length of time subsequent to start of operation of the bagging and packaging machine to thereby increase a gas replacement rate and at a second flow rate lower than the first flow rate subsequent to elapse of the predetermined length of time, such that an amount of the inert gas consumed within the bag is counterbalanced with an amount of the inert gas supplied into the bag.
It is to be noted that the term xe2x80x9camount of the inert gas consumedxe2x80x9d referred to above and hereinafter is intended to means the amount of the inert gas filled into the bag and is retained within the bag after the bag has been completely sealed. Also, the term xe2x80x9camount of the inert gas supplied into the bagxe2x80x9d referred to above and hereinafter is intended to means the amount of the inert gas supplied by the gas supply means with respect to the single bag. Again, the term xe2x80x9ccounterbalanced withxe2x80x9d referred to above and hereinafter is to be understood interchangeable with xe2x80x9cequalized toxe2x80x9d.
According to the foregoing structure, the amount of the inert gas supplied by the gas supply means is at first set to a first flow rate in order to increase the gas replacement rate within the bag and, thereafter, set to a second flow rate lower than the first flow rate so that the amount of the inert gas consumed within the bag can be counterbalanced with, that is, equalized to the amount of the inert gas supplied into the bag. Accordingly, without the gas replacement rate within the bag being lowered, the amount of the inert gas supplied unnecessarily can advantageously suppressed to avoid an unnecessary increase of the amount of the gas used. Also, since the second flow rate is such as to avoid any undesirable blow-up of some of the articles within the bag, the supply of the inert gas at the second flow rate is effective to avoid any possible biting of the bag during a sealing operation of the bag with the articles filled therein, thereby minimizing production of unacceptable bagged products. In addition, since the first flow rate is chosen to be higher than the second flow rate, the inert gas can be filled at a high speed into the bag, thereby facilitating a bagging and packaging operation.
Preferably, the first gas supply control means may continue supply of the inert gas into the bag for a second predetermined length of time subsequent to a temporary halt of the bagging and packaging machine, in a quantity sufficient to avoid reduction of the gas replacement rate within the bag.
In accordance with a second aspect of the present invention, there is also provided a bagging and packaging machine for forming a bag from a strip of bag material and introducing an article into the bag, which includes a gas supply means for supplying an inert gas into the bag to substitute for air contained in the bag, and a first gas supply control means for controlling supply of the inert gas by the gas supply means into the bag. The first gas supply control means is operable to continue the supply of the inert gas into the bag for a second predetermined length of time subsequent to a temporary halt of the bagging and packaging machine, in a quantity sufficient to avoid reduction of the gas replacement rate within the bag.
By way of example, when in the event that the bagging and packaging machine is temporarily brought to a halt with the bagging and packaging operation consequently interrupted, the supply of the inert gas into the bag being filled with the article to be bagged is interrupted, the prior art bagging and packaging machine involves such a problem that the gas replacement rate within the bag decreases with passage of time subsequent to the interruption of the supply of the inert gas. However, according to the present invention, the supply of the inert gas is continued for the predetermined length of time even after the bagging and packaging machine is brought to a halt to thereby avoid any possible reduction of the gas replacement rate. Accordingly, when the bagging and packaging machine once halted resumes its normal operation within a predetermined length of time subsequent to the timing at which the bagging and packaging machine is brought to a halt, a relatively high gas replacement rate can be attained, making it possible to enhance the bagging and packaging operation at a high speed. Also, since the supply of the inert gas is interrupted after a predetermined length of time, the amount of the inert gas used by the gas supply means will not increase unnecessarily.
Furthermore, the present invention in accordance with a third aspect thereof provides a bagging and packaging machine for forming a bag from a strip of bag material and introducing an article into the bag, which includes a gas supply means for supplying an inert gas into the bag to substitute for air contained in the bag, an oxygen detecting means for detecting a state of oxygen remaining within the bag, and a second gas supply control means for controlling supply of the inert gas by the gas supply means into the bag. The second gas supply control means is operable to control the supply of the inert gas into the bag in dependence on the state of the remaining oxygen detected by the oxygen detecting means.
According to the third aspect of the present invention, since the second gas supply control means controls the state of supply of the inert gas based on the state of oxygen remaining within the bag detected by the oxygen detecting means, in the event that, for example, the oxygen detecting means detects an increase of the oxygen remaining rate, the amount of the inert gas supplied from the gas supply means can be adjusted by the second gas supply control means. Accordingly, bagged products each including a bag attaining a high gas replacement rate can be manufactured conveniently.
Preferably, the bagging and packaging machine may further include a warning means for issuing an alarm in the event that a rate of the remaining oxygen detected by the oxygen detecting means exceeds a predetermined value.
The use of the warning means is particularly advantageous in that since when the oxygen remaining rate increases, the warning means can issue an alarm, the attendant worker can easily be advised of increase of the oxygen remaining rate within the bag being formed by the bagging and packaging machine and it is therefore possible to avoid the possibility of a continued production of products having a high oxygen remaining rate.
Also, preferably, the bagging and packaging machine may further include a first storage means for storing an oxygen remaining rate necessary for each of a plurality of kinds of the articles to be bagged.
It is to be noted that the term xe2x80x9cnecessary oxygen remaining ratexe2x80x9d referred herein is intended to means the maximum acceptable amount of oxygen left within the bag and is compatible with a threshold value of the oxygen remaining rate with which the bagged products can be shipped to the market.
Specifically, where the articles to be bagged are potato chips or chocolates or the like, if the first storage means is used to store the flow rate of the inert gas and others based on the shape and the weight thereof, at the time the bagging and packaging operation is to be initiated the bagging and packaging operation can be started by reading out from the first storage means the flow rate of the inert gas appropriate to the bag being filled with the articles. Accordingly, not only can a job of setting the flow rate of the inert gas and others advantageously be simplified, but the hour required to perform the job can also be reduced, thereby enabling the bagging and packaging operation to be performed efficiently. Also, since the amount of the inert gas to be filled in the bag is sufficient if coordinated with the characteristics of the bagged product, the amount of the inert gas which would be otherwise supplied unnecessarily can be suppressed.
Again preferably, the bagging and packaging machine may further include a display means for providing a visual indication of a status of supply of the inert gas from the gas supply means.
The use of the display means for providing the visual indication of the state of the inert gas being supplied from the gas supply means is particularly advantageous in that the attendant worker can visually grape the state of the inert gas being supplied such as the amount of the inert gas remaining in the gas supply means easily and, therefore, he or she knowing how much the inert gas remains in the gas supply means can launch a job of refilling the inert gas prior to the entire amount of the inert gas being consumed. Accordingly, the hour required to complete such a job can be reduced, making it possible for the bagging and packaging machine to perform the bagging and packaging operation efficiently.
The bagging and packaging machine may further include a second storage means for storing a status of supply of the inert gas from the gas supply means or an oxygen remaining rate during operation of the bagging and packaging machine.
According to this structure, the second storage means can store the state of supply of the inert gas from the gas supply means during the operation of the bagging and packaging machine. Therefore, in the event of a trouble occurring in replacement of the air in the bag with the inert gas during the bagging and packaging operation, the state of supply of the inert gas at the time of occurrence of the trouble can be called for from the second storage means so that information necessary to identify a cause of the trouble can be obtained. It is also possible to ascertain whether or not the gas replacement within the bag is properly performed.